Trying to diagnose a problem that has surfaced recently on my truck. I get soft thud on take off. There are no audible noises. It feels like something shifting from back to front. It also does it when coming to a stop when the suspension unloads. I checked the tranny mount with a pry bar and it seems tight. The only other thing I can think of is the slip joint? U joints maybe?

 

U joints, rear axle, gas tank or spare tire.

 

I can eliminate gas tank. Need to double check my motor mounts.

 

I've read that regreasing the slip yoke can help out

 

It's the drive shaft slip joint. Get the prescribed grease from Ford and grease it.

 

Actually dont need the grease from Ford. The grease you pay $45 dollars at ford is about $15 at the local parts store. The actual grease used is a PTFE synthetic grease. I bought a small tub at the marine store for $10.

 

I bought a tub of marine grease at o'reillys for about $10,works great and still have enough to do it another 100 times.

 

Thanks guys, guess I know what I'm doing tomorrow.